In connection with conventional space vehicle or space suit ventilation or respiration air regeneration systems, ventilation or respiration air regeneration systems of the dual-bed or swing-bed type are known and have been successfully employed. In accordance with such systems, an air stream is directed or conveyed in an alternative manner so as to flow, for example, through a first chemical bed, wherein carbon dioxide and/or water vapor are adsorbed and thereby removed from the ventilation or respiratory air stream, while a second chemical bed, which was previously saturated with carbon dioxide and/or water vapor, is being substantially simultaneously regenerated or reconditioned as a result of the exposure of the same to the vacuum of space whereby the carbon dioxide and/or water vapor deposits are discharged from the chemical bed into space under the differential pressure conditions. Subsequently, after a predetermined period of time, the air flow is effectively reversed such that the air stream is now directed or conveyed through the second, regenerated or reconditioned chemical bed while the first chemical bed, which is now saturated with carbon dioxide and/or water vapor deposits, is substantially simultaneously reconditioned or regenerated as a result of the exposure of the same to the vacuum of space. By repeating this dual-bed or swing-bed process at predetermined time intervals, the ventilation or respiratory air stream can be continuously processed while the chemical beds are alternatively regenerated or reconditioned.
A suitable valving arrangement or system is of course necessary to achieve the aforenoted type of alternative routing of the ventilation or respiratory air stream into and out from the two chemical beds, and conventionally, a series of two-way and/or three-way valves, electically sequenced by means of a suitable controller, has been heretofore employed. However, the complexity of such valving, and the piping or conduits defining the air stream paths interconnecting the various valve units, render these conventional systems large and heavy. In addition, the electrical power required to operate the valving is also considerably large. Still further, the amount of ventilation or respiratory air present within a space vehicle or a space suit is a limited resource which must be conserved as much as possible. Accordingly, in accordance with the aforenoted conventional dual-bed or swing-bed systems, the dumping of an entire bed volume of respiratory or ventilation air to the vacuum of space at regular intervals of time is undesirable.
A need therefore exists in the art for a new and improved valving system, and a method of operating the same, to be incorporated within a ventilation or respiration air regeneration system, wherein a single, multi-port spool valve can effect all necessary port connections between the air recirculation or ventilation system or loop, the two chemical beds of the dual-bed or swing-bed system, and the vacuum of space, and wherein, in addition, the two chemical beds are permitted to fluidically communicate with each other, while ventilation or respiratory air is bypassing both chemical beds, such that a bed pressure equalization process is established within the system. In this manner, ventilation or respiratory air within the chemical bed that was previously at cabin or suit pressure is permitted to flow into the chemical bed that was previously at vacuum pressure whereby such process minimizes or limits the subsequent loss of ventilation or respiratory air, to vacuum, to one-half the volume that would otherwise be lost during the entire chemical bed cycling process if such bed pressure equalization process was not achieved.